Rock-cutting drill-bit.



ROCK CUTTING DRILL BIT. APPLIOATION'I'ILED MAR. s, 1913.

Patented Dec. 116, 1913.

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UNITE STATEg PATET IFFIQ.

WALTER E. CARE, OF LITTLETON', COLORADO, ASSIGNQR TU THE INGERSOLL-RAND COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

ROCK-CUTTING DRILL-BIT.

Serial Ne. 751,841.

To all whom it may concern:

Be it known that I, .WALTER E. CARR, a citizen of the United States of America, residing at Littleton, county of Adams, and State of Colorado, have invented a new and useful Rock-Cutting Drill-Bit, of which the following is a specification.

My invention relates to improvements in rock cutting drill bits, and the objects of my invention are: First. To provide a. rock crushing drill bit that will drill a hole of larger diameter than itself and that will drill faster and retain its drilling edges longer than the drills in common use. Second. To provide a hollow or solid drill bit that has a clearance space in the center of its drilling lip. And third, to provide a rock drill bit that is provided with drilling edges and crushing surfaces arranged to drill fast into rock and make true round holes, and that will not rifle or bind in the hole being drilled. I attain these objects by the mechanism illustrated in the accompanying drawings, in which:

Figure 1 is a side elevation of a rock drilling bit embodying my invention. Fig. 2 is a plan view of the rock cutting lip of the drill bit. Fig. 8 is an isometrical view of my rock cutting drill bit and illustrates the parallel arrangement of its cutting edges and their equally proportional diagonal relation to each other, which is an essential feature of my invention. Fig. 4 is aside view showing the drill as it appears when given a quarter rotation from its position shown in Fig. 1.

Similar letters of reference refer to similar parts throughout the several views.

Referring'to the drawings: The numeral 1 designates a bar of drill steel which, as illustrated, is round, hollow drill steel, but which may be of cruciform or octagon or any other form of cross section of either hollow or solid drill steel. This bar of drill steel is provided with a shank end portion 2, at one end, which may be made to fit the drill holding chuck of any rock drilling engine in use, and for this purpose the shank may be left plain, as illustrated, or be arranged to fit into and lock into any special form of drillingv engine chuck.

The numeral 3 desi nates an enlarged head portion which is formed on two sides of the drill steel t rock drilling end, on

the end of which a rock formed.

The rock cutting lip portion 4 of my drill bit comprises a wedge or angular shaped end which extends in a straight line at right angles to the axis of the shank of the drill bit and diametrically across it and forms a single drilling lip, from the apex edge of which sloping sides which form rock crushing surfaces 6 and 7 extend, which are of equal width and of preferably a flat angle. I preferably make thesesides of an angle of about thirty degrees. These angular side edges terminate in rock drilling edges 8 and 9, which are positioned at equal distances, from the apex edge 4 and are also arranged parallel to each other, and they are straight drilling edges, arranged at right angles to the axis of the drill shank, and are also parallel with the apex edge 4, which is positioned centrally between them. This central drilling edge 4 is a trifle longer than the side edges 8 and 9, owing to the curvature of the enlarged head end portion and the angle of the sides of the drill bit, and this center edge extends an equal distance from the axial center of the drill steel and projects forward in advance of the side edges 8 and 9. The center edge 4 forms the advance cutting edge of the drill bit. These side edges 8 and9 are positioned on opposite sides of the central apex cutting edge 4, and they are, in addition to being parallel .to each other, of exactly the same length, and it is an essential feature of my invention that these side cutting edges be of exactly the same "length diagonally across the center edge 4, from their opposite cor 11ers, as shown by the lines 10 and 11 in Fig. 3, in order that the bit will drill a round hole and wear evenly, and thus maintain its full size when Worn or dulled to the limit of its usefulness, without being resharpened. The lip of the drill bit is also provided with a clearance recess 12 which is positioned at the center of the length of the apex edge 4 of the drill bit and extends into its wedge or angular'drilling lip any predetermined distance, but preferably to near its side edge lines 8 and 9. When 'a hollow drill bit is used, as is illustrated in Figs. 1, 2 and 4, this center clearance space registers with and :arrounds theend of the axial aperture 13, through the drill bit, and makes'a clear- Patented Dec. 16, i913.

drilling lip 4 is ance space for the water or air or both, when mingled together, to remove the drillings from the hole being drilled.

The opposite sides 14 of the head end of the drillbit are tapered and flattened out from the diameter of the shank at '15, to leave the end of the drill bit adjacent to its cutting lip at preferably about or close to three-quarters of an inch in thickness when using drill bits ofone and a half inch in diameter, but the thicknessof the drill bit adjacentto the side edges 8 and 9 can be varied as desired. The opposite end side portions 16 and 17 of the enlarged head, end portion of the drill bit adjacent to the wedge shaped drilling lip, are curved concentrically to the axis of the shank portion of the drill bit and are carried'back in a straight head end portion, which is of the same diameter throughout its length, which may be made to extend any predetermined portion of the length of the shank end of the drill bitf I have found in practice, however, that about an inch is sufiicient for the length of this enlarged head end portion, as the drilling ends can be quickly upset and sized and resharpened in dies in pneumatically operated drill sharpening machines as they wear away and grow short from repeated use.

" In operation my improved drill bit will drill a true round hole, will not fitcher and will cut out the bottom of the hole even where the clearance space is formed at its center, and has drilled in practical trials, holes in rock faster than other commonly used shapes of drill bits at present in use in rock drilling engines.

The center recess, which I preferablycall the gift, inasmuch as it is a gift to the cutting edge of the drill bit, as it permits the drill bit to drill a hole an inch and a half in diameter when its cutting edge has been reducedto only an inch in length by the cutting out of this recess in inch and a half -in diameter, operates as follows: When the drill strikes the rock the energy of the blow or impact of the drill bit against the rock shatters'the center of the bottom of the rock in the hole being drilled,

drill bits of an and the actual surface of the apex cutting edge of the drill bit that strikes the rock is reduced to about an inch of the length of the apex edge of the drill bit in a drill having a head of an inch and a half in diameter. The proportion, however, between the cutting lip and this central recess, may be varled relative to each other in bits of dilferent sizes. The object aimed at by this center recess or gift is to make it as large as 1t can be made and still allow the apex cutting edge and its side edges to drill away the whole diameter of the hole.

Having described my invention, what I claim as new and desire to secure by Letters Patent, is:-

In a drill bit comprising a shank portion having an enlarged head end portion curved on two opposite sides concentrically to the axis of the shank of the drill bit, and having the two oppositely arranged sides of the enlarged head portion of the drill bit fiattened and tapered to reduce the thickness of the rock drilling end of the bit from the diameter of the drill steel-to the outer terminal end of the rock drilling lip substantially equally and evenly on each side of the axial center of the drill, a single straight flat wedge or angular shaped rock drilling lip at the terminal end of said drill steel. arran ed to extend diametrically across it at equal istances from its axial center, a rearwardly sloping flat angular side extending from said apex edgeon each side'of its length, said sides being of equal width and length, and a drilling edge at the junction of the flat sides of the drill bit with its flat tapered sides, said side edges being arranged parallel tosaid apex or center edge and of the same diagonal distance across them from their opposite end corners, as specified, and a curved recess extending transversely across said lip at the center of its length.

In testimony whereof I aflix my signature in presence of two witnesses.

WALTER E. CARR. I

Witnesses:

G. SanGnN'r ELLIOTT, v ADELLA M. FowLE. 

